Device for producing audible signals



July 24, 1956 A. e. GRIPARIS DEVICE FOR PRODUCING AUDIBLE SIGNALS 2 Sheets-Sheet 1 3 lnf n for:

drzdrezu 'eogye 'rz' Filed Nov. 16, 1954 July 24, 1956 A. e. GRIPARIS DEVICE FOR PRODUCING AUDIBLE SIGNALS 2 Sheets-Sheet 2 Filed NOV. 16, 1954 @Ziarzzeg United States Patent DEVICE FOR PRODUCING AUDIBLE SIGNALS Andrew George Griparis, Joliet, 111.

Application November 16,1954, Serial No. 469,199

13 Claims. (Cl. 340-405) This invention relates to improvements in audible signal producing devices, such as warning sirens and refers particularly to a siren construction which has desirable directional characteristics and which may be efficiently employed on a moving vehicle.

One of the important features of the present invention resides in a siren construction wherein the passage of air therethrough is impeded to a minimum extent in passing through the impulse-producing agency, which results in the securing of maximum sound with the expenditure of minimum power.

Another important feature of the invention resides in the construction of the siren whereby the sound produced is highly directionalized.

Other important features of the invention will be apparent from the accompanying drawing and following detailed description.

In the drawing,

Fig. 1 is a vertical sectional view of the improved siren.

Fig. 2 is a transverse sectional view taken on line 22 of Fig. 1.

Fig. 3 is a transverse sectional view taken on line 3-3 of Fig. 1.

Fig. 4 is a detailed sectional view taken on line 44 of Fig. 3.

Fig. 5 is a detailed sectional view taken on line 55 of Fig. 2.

Fig. 6 is an exploded view of the components of the improved siren.

Fig. 7 is a front elevation of the improved siren.

Fig. 8 is an exploded view of the rotor of the improved siren.

Referring in detail to the drawing, 1 indicates a base which may be, conveniently, of triangular shape having bolt holes 2 whereby the same may be secured to a suitable support, such, for instance, as the top of a vehicle (not shown). A supporting standard 3 may be secured to the base 1, by screw 4, the upper portion of said standard supporting siren 5.

The siren 5 comprises essentially an electric motor 6, a stator 7 and a rotor 8 which are substantially enclosed by suitable casing elements, to be hereinafter more fully described.

The upper portion of the standard 3 carries a supporting flange 9 upon which the motor 6 is secured by means of screws 10. A rear housing element 11 is secured to the rear end of the motor 6 by means of brackets 12, said housing being tapered rearwardly in a substantially streamlined fashion. The housing 11 is provided with an aperture 13 in which a rubber grommet 14 is positioned. A conductor 15 passes through the grommet 14 and supplies electrical current to the motor 6 from any suitable source of supply (not shown).

The forward portion of the rear housing 11 is flared outwardly as at 16 in Fig. 1 and at its outer periphery the flared portion carries a flange 17. An annular re flector 18 carries a peripheral flange 19 which engages with the flange 17 of the rear housing. The reflector 18 is provided with a curved contour, the purpose of which will be hereinafter more fully described. The reflector 18 adjacent its lower portion is provided with a slot 20 whereby the standard 3 may pass in supporting the motor 6.

At the forward end of the motor 6 the stator 7 is mounted, being secured to the motor by screws or the like 21. The stator 7 comprises a disc and is provided with a plurality of circumferentially spaced apertures 22, the center lines of which are substantially radially disposed. The lateral edges of the apertures are tapered as shown best at 23 in Fig. 4, whereby sharp meeting edges are provided with cooperate with corresponding apertures 24 provided in the rotor 8. The forward edge of the reflector 18 carries a flange 25 which is secured to the stator 7 adjacent the inner circumferential edges of the apertures 22.

The apertures 22 and 24 are substantially the same in shape and area and the circumferential distance between the respective apertures in both the stator and rotor disc is such that at predetermined positions of said rotor with respect to the stator communication between the respective stator apertures and rotor apertures is completely closed.

The rotor 8 comprises a disc 26 having a plurality of outwardly extending circumferentially spaced blades 27. The apertures 24, hereinbefore described, are provided adjacent the outer periphery of the disc 26 and said apertures are similar in number and in spacing with the apertures 22 provided in the stator 7. The disc 26 carries a hub 28 which is secured to shaft 29 of motor 6, said shaft being provided with threads 30 adjacent one end thereof which are engageable by nut 31. The stator 7 is provided with an aperture 32 through which the shaft 29 passes and the disc 26 of the rotor 8 is spaced from the stator 7 by means of spacing sleeve 33 which is positioned in aperture 32.

The blades 27, as shown best in Fig. 2, are slightly offset from the radial and each of said blades constitutes a defining edge of one of the apertures 24. The opposite defining edge 34 of each of the apertures 24 is tapered, as shown best in Fig. 5.

The blades 27 have their outer edges tapered forwardly and inwardly and a shell 35 embraces the outer edges of said blades, said shell conforming with the taper of the outer peripheries of the blades. The inner peripheries of the blades 27 are tapered inwardly and rearwardly as indicated at 36 in Fig. 1.

Mounted upon the outer periphery of the stator 7 is a forward housing member 37, the rear portion of the housing member 37 being provided with a flange 38 which extends rearwardly from the stator 7. The housing 37 conforms substantially with the shape of the shell 35, that is, said housing is tapered forwardly and inwardly. At the forwar d end of the housing 37 said housing is provided with an aperture 39 over which a grating or screening member 40 is positioned.

The construction hereinbefore described has a large number of advantages. The device is so constructed that the flow of air, both when the device is on a moving vehicle and when it is stationary, follows a path of minimum impedence. It will be noted that air enters the forward casing 37 at the opening 39 and leaves the casing through the annular space 41 between the reflector 18 and flange 38 and that the plane of shear, that is, the plane made by the adjacent faces of stator and of the disc 26 of the rotor, is at substantially right-angles to this path of movement of the. air. In many sirens heretofore proposed, the air on entering the siren must be diverted at right-angles to pass through the plane of shear, that is, the rotors and stators are substantially cylindrical, the entering air first moving along the axis of the cylinder and then being diverted to pass through the shear plane istics.

at the lateralsurface of the cylinder. Thus, in the construction of the present invention, this right-angle diversion of the air prior to passing through the planeof shear, is avoided and afreer passage of the air results.

The effect which is provided by the foregoing construction may be described broadly as an axial flow. By axial. flow referenceismade to' the general flow of air through the rotor and shear plane being aligned with the axis of the rotor. In conventional sirens, the flow of air is radial to a cylindrical shear plane. The axial flow type siren described has unusual characteristics, particularly when mounted as a signaling device on a moving vehicle. The air entering the forward portion of the siren due to the forward motion of the vehicle augments the action at the, shear plane. Further, when the sound radiates outwardly it is constrained to flow axially, thereby giving its'full eifect ahead of the vehicle, and not dissipating the bulk of the signal radially.

In addition, in many prior art sirens the sound produced at the plane of shear is propagated both forwardly and rearwardly aswell as radially at the plane of shear and, thus, the siren possesses poor directional character- In the present invention, sound generated at the plane of shear moves directly forwardly from the plane of shear with minimum impedance, that is, with no abrupt changes in direction, through the opening 39. In addition, sound generated rearwardly of the plane of shear is reflected by the curved reflector 18 and the components thereof move both forwardly and radially but not rearwardly. Thus, more of the sound generated in the present structure moves forwardly than in devices heretofore proposed giving desirable directional characteristics to the siren.

Another feature of the present invention resides in the contour of the outer peripheries of the blades 27 and the provision of the shell 35. This is conducive to the supply of an adequate amount of flowing air passing the plane of shear even when the vehicle upon which the sirenmay be mounted is stationary. It can be, seen that, even with the device stationary,.the rotation of the rotor causes a superatmospheric air pressure within the shell in the vicinity of the plane of shear due to the centrifugal motion imparted to the air within the shell, causing the air to move outwardly and rearwardly along the inner surface of the shell. This centrifugal force imparted to the air, of course, is also present when the device is in forward motion, but is more pronounced in its effect when the device is stationary.

Another advantage in the present construction resides in the fact that the shape of the rotor blades and the contour of the shell permits the inward and forward tapering.

of the forward casing 37 which streamlines the forward portion of the device and enhances its general appearance.

One of the important features of the device comprising the present invention resides in the construction thereof whereby when the motor is deenergized and the rotor happens to stop in such a position as to bring apertures 22 and 24 into communication, the air movement within the siren caused by movement of the vehicle upon which the siren is carried will cause the rotor to move so as to close communication between said apertures. If the rotor would remain in such a position that the apertures 22 and 24 were in communication, the air passing through the siren, due to the motion of the vehicle, would carry dust,

insects, snow and the like into the siren and, if thedifferences existwithin the rotor, that is, a condition of equilibrium exists. However, it is not intended that the operation of the present invention be limited to this hypothesis.

In this connection it will be noted that the apertures. 24 in the rotor disc are unsymmetrically disposed with respect to the space between adjacent blades 27, that is, a defining edge of each aperture is disposed at a surface of a blade whereas the opposite defining edge of the aperture is spaced from an adjacent blade. Thus, it is possible that air which may pass through the rotor, at right angles to Fig. 2; for instance, will move at higher velocity in alignment with an aperture 24 (when. said aperture is in communication with an aperture 22) than the air passing at right-angles to the solid portions of the rotor disc. Hence, on one side of each blade the pressure may be less than the pressure on the opposite side of each blade. A torque may thus be exerted upon the rotor whichfwill rotate the rotor until communication between apertures 22 and 24 is closed at which time no pressure differential exists within the rotor- Thus, when apertures 22 and 24 are in communication an unstable condition is brought about which tends slowly to rotate the rotor until communication is broken between the apertures.

I claim as my invention:

1. An axial flow siren, comprising in combination, 'a

casing having a forward portion and a rear portion, an electric motor having a shaft carried in said casing, the forward portion of said casing being provided with an inlet opening in substantial alignment with the axis of the shaftof said motor, a stator di'sc carried in said casing rearwardly of said opening and having its plane at substantially right-angles to said motor shaft, a rotor carried upon said motor shaft, said rotor comprising a disc portion disposed, adjacent and substantially in plane-parallel relationship to said stator, and circumferentially spaced blades carried by said rotor disc, said stator and said rotor.

disc each being provided with corresponding circumferentially spaced openings, said casing intermediate the forward portion and said rear portion and rearwardly of said stator being provided with an outlet opening.

2. An axial flow siren, comprising in combination, a casing having a forward portion and a rear portion, an electric motor having a shaft carried in said casing, the forward portion of said casing being provided with an inlet opening in substantial alignment with the axis of the shaft of said motor, a stator disc carried in said casing rearwardly of said opening and having its plane at sub stantially right-angles to said motor shaft, a rotor carried upon said'motor shaft, said rotor comprising a disc portion disposed adjacent and substantially in plane-parallel relationship to said stator, and circumferentially spaced blades carried by said rotor disc, said stator and said rotor disc each being provided with corresponding circumferentially spaced openings, said casing intermediate the for- Ward portion and said rear portion and rearwardly of said stator being provided with. an outlet opening, and a sound reflector plate carried by said casing adjacent said outlet opening for reflecting sound generated by said stator and rotor radially and forwardly.

3. An axial flow siren, comprising in combination, a casing having a forward portion and a rear portion, an electric motor having a shaft carried in said casing, the forward portion of said casing being provided with an inlet opening in substantial alignment with the axis of the shaft of said motor, a stator disc carried in said casing rearwardly of said opening and having its plane at substantially right-angles to said motor shaft, a rotor carried upon said motor shaft, said rotor comprising a disc portion disposed adjacent and substantially in plane-parallel relationship to said stator, and circumferentially spaced blades carried by said rotor disc and extending forwardly of said rotor disc, said stator and said rotor disc each being provided with corresponding circumferentially spaced openings, the openings in said rotor disc being disposed intermediate said rotor blades, said casing intermediate the forward portion and said rear portion and rearwardly of said stator being provided with an outlet opening. I

4. An axial flow siren, comprising in combination, a casing having a forward portion and a rear portion, an electric motor having a shaft carried in said casing, the forward portion of said casing being provided with an inlet opening in substantial alignment with the axis of the shaft of said motor, a stator disc carried in said casing rearwardly of said opening and having its plane at substantially right-angles to said motor shaft, a rotor carried upon said motor shaft, said rotor comprising a disc portion disposed adjacent and substantially in plane-parallel relationship to said stator, and circumferentially spaced blades carried by said rotor disc and extending forwardly of said rotor disc, said stator and said rotor disc each being provided with corresponding circumferentially spaced openings, each opening in said rotor disc being defined on a lateral edge thereof by one of said rotor blades, said casing intermediate the forward portion and said rear portion and rearwardly of said stator being provided with an outlet opening.

5. An axial flow siren, comprising in combination, a casing having a forward portion and a rear portion, an electric motor having a shaft carried in said casing, the forward portion of said casing being provided with an inlet opening in substantial alignment with the axis of the shaft of said motor, a stator disc carried in said casing rearwardly of said opening and having its plane at substantially right-angles to said motor shaft, a rotor carried upon said motor shaft, said rotor comprising a disc portion disposed adjacent and substantially in plane-parallel relationship to said stator, and circumferentially spaced blades carried by said rotor disc, said blades extending forwardly from said rotor disc and having their outer peripheral edges inclined forwardly and inwardly toward the central portion of said inlet opening, said stator and said rotor disc each being provided with corresponding circumferentially spaced openings disposed adjacent the peripheries of said stator and rotor disc, said casing intermediate the forward portion and said rear portion and rearwardly of said stator being provided with an outlet opening.

6. An axial flow siren, comprising in combination, a casing having a forward portion and a rear portion, an electric motor having a shaft carried in said casing, the forward portion of said casing being provided with an inlet opening in substantial alignment with the axis of the shaft of said motor, a stator disc carried in said casing rearwardly of said opening and having its plane at substantially right-angles to said motor shaft, a rotor carried upon said motor shaft, said rotor comprising a disc portion disposed adjacent and substantially in plane-parallel relationship to said stator, and circumferentially spaced blades carried by said rotor disc, said blades extending forwardly from said rotor disc and having their outer peripheral edges inclined forwardly and inwardly toward the central portion of said inlet opening, an annular shell carried upon the outer peripheries of said rotor blades, said shell being provided with a central opening adjacent said inlet opening, said stator and said rotor disc each being provided with corresponding circumferentially spaced openings disposed adjacent the peripheries of said stator and rotor disc, said casing intermediate the forward portion and said rear portion and rearwardly of said stator being provided with an outlet opening.

7. An axial flow siren, comprising in combination, a casing having a forward portion and a rear portion, an electric motor having a shaft carried in said casing, the forward portion of said casing being provided with an inlet opening in substantial alignment with the axis of the shaft of said motor, a stator disc carried in said casing rearwardly of said opening and having its plane at substantially right-angles to said motor shaft, a rotor carried upon said motor shaft, said rotor comprising a disc portion disposed adjacent and substantially in planeparallel relationship to said stator, and circumferentially spaced blades carried by said rotor disc, said stator and said rotor disc each being provided with corresponding circumferentially spaced openings, said casing intermediate the forward portion and said rear portion and rearwardly of said stator being provided with an annular outlet opening, and a substantially annular sound reflector positioned adjacent said outlet opening for reflecting sound generated by said stator and rotor annularly and forwardly.

8. An axial flow siren, comprising in combination, a casing having a forward portion and a rear portion, an electric motor having a shaft carried in said casing, the forward portion of said casing being provided with an inlet opening in substantial alignment with the axis of the shaft of said motor, a stator disc carried in said casing rearwardly of said opening and having its plane .at substantially right-angles to said motor shaft, a rotor carried upon said motor shaft, said rotor comprising a disc portion disposed adjacent and substantially in plane-parallel relationship to said stator, and circumferentially spaced blades carried by said rotor disc, said stator and said rotor disc each being provided with corresponding circumferentially spaced openings, the opposite lateral edges of said stator openings being tapered and one lateral edge of each rotor opening being tapered, the opposite lateral edge of each rotor opening being defined by a side of a rotor blade, said casing intermediate the forward portion and said rear portion and rearwardly of said stator being provided with an outlet opening.

9. An axial flow siren comprising in combination, a casing, a stator in said casing provided with a plurality of circumferentially disposed apertures adjacent the periphery of the stator, a rotor comprising a rotor disc disposed for rotation in plane-parallel relationship adjacent said stator, a plurality of blades carried by said rotor and disposed substantially radially and with their planes transverse to said rotor disc, said rotor disc being provided with a plurality of circumferentially disposed apertures adjacent its periphery, said rotor apertures having opposite substantially radial defining edges and being registrable with the apertures in said stator at predetermined positions of said rotor relative to said stator, one radial defining edge of each rotor aperture comprising a blade and the opposite radial defining edge of each rotor aperture being spaced from an adjacent blade whereby said rotor apertures are unsymmetrically disposed in the space between adjacent blades.

10. A power driven axial flow siren comprising, in combination, a power driven shaft, a rotor secured to the power shaft and characterized by a rotor disc, a plurality of substantially radial vanes joined at their rear portions to the rotor disc, a plurality of ports in the rotor disc between the vanes, and a shroud surrounding and secured to the ends of the vanes, and the periphery of the rotor disc, the shroud tapering progressively forwardly, a stator disc immediately behind the rotor disc having ports which register sequentially with the rotor ports, a housing surrounding the siren elements having an aperture at its forward portion to admit air for an axial flow through the rotor, and exhaust means for expelling the air after shearing when the air passes through the registered rotor and stator ports.

11. A power driven axial flow siren comprising, in combination, a power source for driving a shaft, a rotor disc mounted to the drive shaft with vanes extending radially from the drive shaft, the rotor disc defining ports adjacent the periphery of the rotor and between the radial vanes, a stator disc oriented behind the rotor with ports positioned to sequentially overlap the rotor ports, a parabolic annular shroud surrounding the rotor vanes at their tips, and a housing surrounding the rotor and stator with a forward opening proportioned to admit air axially into the rotor which is drivingly sheared as the rotor ports and stator port's overlap, and a parabolic at the rear of the stator to deflect the exhaust air and sound;

12. An axial'flow siren. characterized bya coaxial circular stator and rotor each having registering ports adjacent their circumference, a plurality of substantially radial vanes extending forwardly from the rotor, and a shroud surrounding the vanes with an aperture at its forward portion admitting air to the rotor which is drivingly forced through the rotor ports and stator ports. and sheared as the ports move sequentially in and out of register. 7

13. In an axial flow siren having a housing with aforward inlet aperture, and permanent stator disc with peripheral ports, a rotor characterized by a disc'having ports 8 which register with the stator ports, substantially radial vanes extending forwardly from.- the back plate, and a shroud surrounding the vanes and secured to their endstapering forwardly-to the housing forward aperture", and

means for drivinglyrotating therotor.

References Cited in the file ofthis patent UNITED STATES PATENTS 

